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Chemical Sampling Information (CSI)
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General Description

Synonyms: Diesel exhaust component; Dinitrogen tetroxide (N2O4); NO2; Nitrogen peroxide; Nitrogen tetroxide

OSHA IMIS Code Number: 1903

Chemical Abstracts Service (CAS) Registry Number: 10102-44-0

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: QW9800000

Department of Transportation Regulation Number (49 CFR 172.101) and 2012 Emergency Response Guidebook [4 MB PDF, 392 pages]: 1067 124

NIOSH Pocket Guide to Chemical Hazards - Nitrogen Dioxide: Physical description, chemical properties, potentially hazardous incompatibilities, and more

Exposure Limits and Health Effects

Exposure Limit

Limit Values

HE Codes

Health Factors and Target Organs

OSHA Permissible Exposure Limit (PEL) - General Industry
See 29 CFR 1910.1000 Table Z-1

5 ppm
(9 mg/m3) Ceiling


Chronic bronchitis, emphysema
HE15 Eye, nose, and upper respiratory irritation

OSHA PEL - Construction Industry
See 29 CFR 1926.55 Appendix A

5 ppm
(9 mg/m3) Ceiling


Chronic bronchitis, emphysema

HE15 Eye, nose, and upper respiratory irritation

OSHA PEL - Shipyard Employment
See 29 CFR 1915.1000 Table Z-Shipyards

5 ppm
(9 mg/m3) Ceiling


Chronic bronchitis, emphysema

HE15 Eye, nose, and upper respiratory irritation

National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL)

1 ppm
(1.8 mg/m3) STEL


Mild headache

HE10 Bronchiolitis obliterans
HE11 Acute pulmonary edema; lower respiratory irritation (cough, dyspnea)
HE15 Eyes, nose, and throat irritation

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) (2012)

0.2 ppm
(0.38 mg/m3)


Lower respiratory irritation


1 ppm
(1.8 mg/m3) STEL



National Toxicology Program (NTP) carcinogenic classification: Not listed

International Agency for Research on Cancer (IARC): Not listed

U.S. Environmental Protection Agency (EPA) carcinogenic classification: Not listed

EPA Inhalation Reference Concentration (RfC): Not established

Agency for Toxic Substances and Disease Registry (ATSDR) Inhalation Minimal Risk Level (MRL): Not established

NIOSH Immediately Dangerous to Life or Health (IDLH) concentration: 20 ppm

Notes on Other Potential Health Effects and Hazards

  1. Nitrogen dioxide may increase bronchoconstriction in asthmatics at concentrations as low as 0.1 ppm (Roger et al. 1990).
  2. Nitrogen dioxide is a component of silo gas thought to cause the sometimes fatal "silo filler's disease" (Douglas et al. 1989).
  3. Nitrogen dioxide itself is not combustible, but it may enhance the combustion of other chemicals (NIOSH/IPCS 2003).
  4. Nitrogen dioxide may exert an allergic response on the bronchial epithelium and may predispose the respiratory tract to viral infections (Pathmanathan et al. 2003; Frampton et al. 2002).
  5. NO2 exposure may reduce bronchociliar activity (Helleday et al. 1995).
  6. Even at low exposures, NO2 may increase asthmatic exacerbations following respiratory infections (Linaker et al. 2000).

Date last revised: 09/06/2012

Literature Basis

  • ACGIH: Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Nitrogen Dioxide. 2012.
  • Douglas, W.W., Hepper, N.G., and Colby, T.V.: Silo-filler's disease. Mayo Clin. Proc. 64(3): 291-304, 1989.
  • Frampton, M.W., Boscia, J., Roberts, N.J. Jr., Azadniv, M., Torres, A., Cox, C., Morrow, P.E., Nichols, J., Chalupa, D., Frasier, L.M., Gibb, F.R., Speers, D.M., Tsai, Y., Utell, M.J.: Nitrogen dioxide exposure: effects on airway and blood cells. Am J Physiol Lung Cell Mol Physiol. 282(1):L155-65, Jan 2002.
  • Helleday, R., Huberman, D., Blomberg, A., Stjernberg, N., Sandstrom, T.: Nitrogen dioxide exposure impairs the frequency of the mucociliary activity. Eur Respir J. 8(10):1664-8, Oct 1995.
  • Linaker, C.H., Coggon, D., Holgate, S.T., Clough, J., Josephs, L., Chauhan, A.J., Inskip, H.M.: Personal exposure to nitrogen dioxide and risk of airflow obstruction in asthmatic children with upper respiratory infection. Thorax. 55(11):930-3, Nov 2000.
  • NIOSH: Criteria for a Recommended Standard: Occupational Exposure to Oxides of Nitrogen (Nitrogen Dioxide and Nitric Oxide). 1976.
  • NIOSH: Occupational Health Guideline for Nitrogen Dioxide. 1978.
  • NIOSH/IPCS: International Chemical Safety Cards - Nitrogen dioxide. 2003.
  • Pathmanathan, S., Krishna, M.T., Blomberg, A., Helleday, R., Kelly, F.J., Sandstrom, T., Holgate, S.T., Wilson, S.J., Frew, A.J.: Repeated daily exposure to 2 ppm nitrogen dioxide upregulates the expression of IL-5, IL-10, IL-13, and ICAM-1 in the bronchial epithelium of healthy human airways. Occup Environ Med. 60(11):892-6, Nov 2003.
  • Roger, L.J., Horstman, D.H., McDonnell, W., Kehrl, H., Ives, P.J., Seal, E., Chapman, R., Massaro, E.: Pulmonary function, airway responsiveness, and respiratory symptoms in asthmatics following exercise in NO2. Toxicol Ind Health. 6(1):155-71, Jan 1990.
Monitoring Methods used by OSHA

Laboratory Sampling/Analytical Method:

  • sampling media: Molecular Sieve (Water washed, Triethanolamine impregnated)
    maximum volume: 3 Liters
    maximum flow rate: 0.2 L/mi (STEL or Ceiling)
    current analytical method: Ion Chromatography; IC
    method reference: OSHA Analytical Method (OSHA ID-182)
    method classification: Fully Validated
    note: Submit as a separate sample.

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